Stable water-dispersed organic nanoparticles: preparation, optical properties, and cell imaging application.

Water-dispersed organic nanoparticles (NPs) constructed by the conjugated molecule 2,5,2',5'-tetra(4'-N,N-diphenylaminostyryl)biphenyl (DPA-TSB) with a high luminescence and large two-photon absorption (TPA) section were fabricated via the reprecipitation method. The average size of the NPs can be controlled from 40 nm to 80 nm by adjusting the reprecipitation conditions. The NPs in water dispersions showed high aggregative and optical stability, which were due to contributions from the special cruciform configuration and amorphous nature of DPA-TSB molecules. The cellular uptake behavior of DPA-TSB NPs was investigated to show their cell staining capabilities as nanoprobes using a confocal microscopy test in vitro. The results demonstrated that DPA-TSB NPs were readily internalized into cytoplasm with no apparent toxicity for up to 24 h, implying excellent imaging capabilities.